Ingredients:
14 to 16 ouncespeeled or unpeeled pearl onions, fresh or frozen and thawed
Extra-virgin olive oil, for sautéing
5 ouncespancetta, cut into lardons (about 1 cup)
8 ouncesbutton mushrooms, halved
1/4 cupcognac
3 cupsfish or seafood stock
7 black peppercorns
5 (2-inch) parsley stems
3 thyme sprigs
1 dried bay leaf
1 garlic clove, peeled
1 clove
Kosher salt, to taste
1 (750-milliliter) bottle dry Riesling
20 mussels, scrubbed and debearded
8 ouncesskin-on halibut (or monkfish), sliced into hearty chunks
8 ouncesskin-on sea bass (or perch), sliced into hearty chunks
8 ouncesArctic char (or salmon), sliced into hearty chunks
12 to 15 U/20 shrimp, peeled and deveined
2 tablespoonsall-purpose flour
2 tablespoonsunsalted butter, at room temperature
3 tablespoonschopped flat-leaf parsley leaves
1 tablespoonchopped tarragon leaves
Toasted baguette or sourdough, or cooked long noodles
Directions:
If your onions are not peeled, bring a small pot of water to boil. Add the onions and cook for 2 minutes. Drain them in a colander and run under cold water until cool enough to handle. Peel. (If your onions are thawed from frozen and already peeled, skip this skip.)
In a wide pot or Dutch oven over medium-low heat, add a big drizzle of oil and cook the pancetta until crispy, 10 to 12 minutes, stirring occasionally. Use a slotted spoon to transfer the pancetta to a large bowl.
Add the onions to the same pan, agitating the pan to coat them in the hot fat (you can add another drizzle of oil if the pan looks dry). Sauté over medium-low until they start to brown, 5 to 7 minutes, stirring occasionally.
Add the mushrooms and agitate the pan again. Over medium, sauté the mushrooms until golden and soft, about 7 minutes, stirring occasionally.
Add the cognac and reduce almost completely, about 1 minute. Transfer the onions, mushrooms, and any remaining liquid to the bowl of pancetta.
Add the stock to the pot and stir any liquor residue into the stock. Raise the heat to medium.
While that heats up, wrap the peppercorns, parsley stems, thyme sprigs, bay leaf, garlic clove, and clove in a piece of muslin (or extra-fine cheesecloth) and secure with kitchen twine. Add this bouquet garni to the stock, along with ½ teaspoon salt and the wine. Bring to a boil over high heat.
Add the mussels, agitate the pan so they settle into an even later, cover the pot, and lower the heat to medium-high. After about 5 minutes, their shells should have opened. Use a slotted spoon to strain and transfer them to a large bowl. Discard any mussels that haven’t opened. Remove and discard the bouquet garni.
Add the pancetta, onions, and mushrooms, plus any accumulated juices to the stock mixture and return to a gentle simmer. Add the halibut and poach for 3 minutes, until the flesh turns fully opaque, lowering the heat as needed so the mixture barely bubbles, then use a slotted spoon to transfer the halibut to the bowl with mussels. Add the sea bass and poach for 2 minutes, until opaque everywhere but in the middle, then transfer to the bowl with mussels. Add the Arctic char and poach for 2 minutes, until opaque everywhere but in the middle, then transfer to the bowl with mussels. Add the shrimp and cook for 2 to 3 minutes, until nearly opaque in the center, then transfer to the bowl with the mussels.
In a small bowl, use a spoon to mash the flour into the butter until fully incorporated—it will resemble a thick paste. Add to the pot and stir regularly for 5 to 7 minutes, until the broth is somewhat thickened.
Taste and adjust the salt as needed. Gently add back all of the fish, mussels, and shrimp and stir to incorporate. Ladle into wide shallow bowls and sprinkle with parsley and tarragon. Serve with bread for mopping up the sauce, or over noodles.